Automatic broadcasting station selector and volume control



April 16, 1940- c. o. NELsoN 2,197,312

I UTOIATIC BROADCASTING STTION SELECTOR bAND VOLUME CONTROL Filled Oct.28, 1938 4 Sheets-Sheet 1 April 1s, 1940. l c o, NELSQ'N 2,197,312

AUTOMATIC BROADCASTING STATION SELECTOR AND VOLUME CONTROL Filed Oct.28, 1938 4 Sheets-Sheet 2 eww@ tm @was ajlgyn iN ENTOR April 1s, 1940.o, NELSN' 2,197,312

AUTOIATIVIC BROADCASTING STATION SELECTOR AND VOLUME CONTROL Filed oct.28. 195e 4 sheets-sheet :s

INVENTOR ATTORN EYS April 16, 1940. Q oa NELSON 2,197,312

AUTUIATIC BROADCASTING STATION SELECTOR AND VOLUME ,CONTROL Filed Oct.28, 1938 4 Sheets-Sheet 4 T0 SET mZzls ajlfelmef' A ATTORNEYS PatentedApr. 16, 1940 UNITED STATES AUTOMATIC BROADCASTING STATION SELECTOR ANDVOLUME CONTROL Curtis 0. Nelson, Belleville, Ill. Application October28, 1938, Serial No. 237,563

4 Claims.

My invention relates to radio receivers and has among its objects andadvantages the provision of an automatic broadcasting station selectorand volume control.

An object of my invention is to provide novel means by which a radioreceiving set may be automatically tuned to preselected broadcastfrequencies at predetermined times and in which novel volume controlmeans are incorporated.

The invention embodies novel selecting means whereby the apparatus is sodesigned as to automatically tune different stations in and out atpredetermined times. The invention may be associated with a radioreceiver of conventional design and is so associated therewith as not tointerfere with the manual control of the receiver independently of theautomatic feature. The station selector embodies means whereby selectedstations may be tuned in and out more 20.A than once, for example,during a twelve hour period.

While radio waves received by a receiving set usually vary considerablyin strength, the automatic volume control is so designed as to maintainthe volume of sound from the receiving set substantially uniform. Thevolume control embodies means which may be precisely set or adjusted tothe different broadcasting stations. Atmospheric conditions, distanceand the like may weaken or strengthen signals. Precise adjustment isassured through the medium of a resistor which may be employed forcorrecting deficiencies in the automatic volume control.

In the accompanying drawings:

i Figure 1 is an elevational view of the selector drum and the automaticvolume control;

Figure 2 is a top plan view of the structure of Figure 1;

Figure 3 is a sectional view along the line 3--3 oi Figure 1;

Figure 4 is a sectional view along the line 4-4 of Figure l;

Figure 5 is a perspective view illustrating the manner in which theselector pins are adjustably related to the selector drum;

Figure 6 is a view illustrating a switch;

Figure 7 is a view of the motor switch; and

Figure 8 is a diagrammatic view of the motor circuit.

50. In the embodiment selected to illustrate my invention, I make use ofa radio receiver cabinet, a portion of which is illustrated at I8.Cabinet I0 is provided with a shelf I2 upon which I mount a selectordrum I4. Drum I4 includes 55.y end flanges I6 and I8, see Figs. 1 and 3,con- (Cl. Z-20) nected with hubs 20 through the medium of spokes 22.Hubs 20are bored at 24 for the reception of a shaft 26 fxedly related tothe hubs by means of set screws 28. Shaft 26 is rotatably journaled inbearings 30 formed at 5 the upper endsof brackets 32 and 34. Brackets 32and 34 are Secured to the shelf I2 by screws 36.

Shaft 26 is connected with a shaft 38 through the medium of a iiexiblecoupling 40. Flexible 10 coupling 40 is bored for the reception of theends of the shafts 26 and 38, and the coupling is made secure by setscrews 42. Shaft 38 is driven by an electric clock 44 which may be ofconventional design. The flexible coupling 40 15 dampens any vibrationincident to operation of the clock. The cabinet panel 46 is bored at 48for the reception of the clock so as to bring it substantially withinthe contour of the cabinet. The clock may include a. flange 50 lying 20adjacent the outer face of the panel 46. In the present invention, theclock operates continuously so that the selector drum I4 is rotatedWithout interruption.

Flange I6 is formed integrally with the'pe- 25 ripheral Wall 52-of theselector drum. Wall 52 is provided with a plurality of slots 54 and isformed integrally with the ange IIi.y These parts may be formed bydiecasting from suitable material such as zinc, white metal, oralumi-.30 num. Flange I8 is provided with a circumferential ledge 56which supports the opposite end of the peripheral wall 52, and thelatter is provided with a ange 58 fixedly secured to the iiange `I8 byscrews 60. Flange 58 extends com- 35 pletely about the peripheral wall52 and is of somewhat larger diameter than the wall.

Peripheral Wall 52 includes forty-eight slots 54 which represent fifteenmi-nute periods of time for a twelve hour period. 'I'he selector drum is40 positioned adjacent the cabinet side wall 62 and extends across anopening 64 in the wall. The opening in the wall may be provided with anornamental liner 66, which liner is provided with division lines 68 toprovide zones 10, 12, 45 "I4, 16, 18, 80, y82 and 84. Zone 'I0 isdesignated neutral, as at 86, while zone I2 is designated off, as at 88.Zone I4 is designated on, as at 90, while zone 84 is designated neutral,as at 92. Zones T6, 18, and 82 are designated dif- 50 ferentbroadcasting stations, as indicated at 94.

The peripheral wall 52 of the selector drum carries a plurality of pins96. The pins 96 are slidably related to the slots 54, and two pins areprovided for each slot. Figs. l and 5`best 55 through the medium ofconventional drives.

illustrate the relation between the pins 96 and the slots 54. The wall52 is provided with longitudinal ribs 98 intermediate the slots orcentrally of the ribs |00. Ribs 98 are considerably narrower than theribs |00. Pins 96 have close fitting relation with the walls of theirrespective slots 54, and each pin carries a flange |02 which bearsagainst the outer faces of their adjoining ribs |00. Each pin 96 alsoincludes a bowed spring |04 which bears against the inner faces of theiradjoining ribs |00. Springs |04 are bent back upon themselves at |06 soas to provide gentle curvatures facilitating relative sliding movementof the pins longitudinally of the slots 54. The springs |04 are fixedlyconnected with the pins 96 and are under tension so as to frictionallysupport the pins. However, the pins may be manually shifted.

Figure 2 illustrates the pins 96 distributed over the general area ofthe peripheral wall 52. The distribution of the pins 96 will depend uponthe broadcasting station or stations to be tuned in at a predeterminedtime or times. The selector drum |4 is rendered inoperative forautomatic tuning by shifting the pins 96 to positions on the selectordrum |4 corresponding to the neutral zones 10 and 84.

Floor |2 carries two brackets |08 and ||0. Bracket |08 and theupstanding flange |2 of the bracket ||0 rotatably support a shaft ||4.To one end of the shaft ||4 I connect a worm gear ||6 arranged in meshwith the worm ||8 driven by the electric motor |20. Bracket |08 is madesecure by screws |22, while the bracket ||0 is anchored to the oor byscrews |24. I interpose a slip clutch |26 in the shaft ||4. The manuallyrotated shaft |28 for turning the condenser of the set extends throughan opening |30 in the wall 46 in the usual manner, and the opposite endof the shaft is rotatably journaled in the flange |32 4of the bracket||0. Shaft ||4 is Xedly connected with a flange |34 having a V-shapedlug |36 normally extending into the groove |38 in a disc |40 splined tothe shaft |28 for rotation therewith but slidable longitudinallythereof. Between the disc |40 and the ange |32, I interpose acompression spring 42 which urges the disc |48 against the disc |34.Spring |42 causes the lug |36 to have such holding relation with thegrooved disc ||4 as to impart rotation to the shaft |23 through rotationof the shaft ||4 when the motor |20 is operating. Shaft |28 may beprovided with a gear or wheel |44 which may be operatively connectedwith the variable condenser To the outer end of the shaft |28, I connecta knob |46 so that the shaft |28 may be manually rotated for tuningpurposes in the usual way. The variable condenser should be of the typein which the rotary section may be rotated continuously in onedirection.

With the motor |20 inoperative, the condenser may be tuned manuallythrough the medium of the shaft |23. Manual rotation of the shaft |28will cause the lug |32 to cam the disc |40 toward the flange |32 againstthe tension of the spring |42. With the motor |20 inoperative, shaft ||4remains stationary. For automatic tuning purposes, the motor |20 rotatesthe shaft |28 through the medium of the shaft ||4 for tuning thecondenser.

Upon the shaft ||4 I fixedly secure a plurality of stops |46', |48, |50and |52. Stop |46' is aligned with the zone 16, while the stop |48 isaligned with the zone |18. Stop |50 is aligned with the zone 80, whilestop |52 is aligned with the zone 82. In Fig. 2, I illustrate fourstation zones only, but the limited number is for the purpose ofillustration only. More or less zones may be employed, since theconstruction of the selector drum 4 and its associated mechanism remainsthe same regardless of the number of the broadcasting zones.

Motor |20 operates to rotate the shaft |4 in the direction of the arrow|54, see Fig. 1. Brackets 32 and 34 support a shaft |56 which parallelsthe shaft |4. Upon the shaft |56, I mount companion stops |58, |60, |62and |64. Companion stops |58 to |64 are aligned with the stops |46 to|52, respectively. Companion stops |58 to |64 are loosely mounted on theshaft |56 for rotation thereon. The stops are supported in spacedrelation by spacers |66, and pins |68 extending through the shaft |56restrain the assembled companion switch arms and the spacers |66 fromrelative movement longitudinally of the shaft |56.

Selector drum I4 is clock rotated in the direction of the arrow |10, seeFig. 1, and pins 96 are adjustable on the selector drum for camming thecompanion stops to positions for abutting relation with the stops |46 to|52. Fig. 1 illustrates the companion stop |64 pivoted to a horizontalposition for bringing its end |12 into abutting relation with the stop|52 to prevent further rotation of the shaft ||4. Only one companionstop is pivoted to a horizontal position at a time, since each stop isassociated with one broadcasting station only.

Motor |20 rotates the shaft ||4 for turning the condenser of the radioreceiver. One pin 96 is aligned centrally of one of the zones 16 to 82,depending upon the broadcasting station selected, and the pin 96selected depends upon the time at which the selected broadcastingstation is to be tuned in. Flange 58 includes a diagonal face |14 uponwhich time indicia |16 are printed. The indicia are distributed to alignwith the slots 54 for representing fifteen minute periods of time. Fig.1 illustrates one of the pins 96 in the |18 position as being in cammingrelation with the short end of the companion stop |64. The long end ofthe companion stop is characterized by an overbalancing weight in such adegree as to cause the long end to pivot downwardly as soon as the pin96 in the |18 position has moved out of camming relation with the shortend. Pin 96 in the |18 position has been aligned with the zone 82. Sincethe pin adjustment and other cooperating parts associated with each ofthe zones 16 to 84 operate in the same manner, the description of oneadjustment will apply to all the zones.

With the stop |52 and the companion stop |64 positioned according toFig. 1, the condenser of the receiver will be properly tuned to thedemands of the broadcasting station represented by the zone 82.Referring to Fig. 1, the companion stop |64 reaches a horizontalposition substantially at the time that the stop |52 is brought intoabutting relation therewith. The stops |46', |48, |50 and |52 are cutaway at |80 so as to provide cam faces of gentle angularity cooperatingwith the ends of their respective companion stops to prevent touchingbetween the parts before the companion stops are moved completely totheir stopping positions. However, the parts are so arranged that thecompanion stops are cammed to their abutting positions immediatelybefore their respective stops are brought into abutting relationtherewith. Means is provided for closing the circuit through the motor|20 at wire 268 through the medium of a wire 284.

such time as to bring the stop |52 into abutting relation with thecompanion Stop |64 at the proper time. Flange |58 is recessedperipherally at |82 to provide cam elevations |84 aligning with theslots 54. One such cam elevation is provided for each of the slots. Thepin 96 in the |18 position has camming relation with the short end ofthe companion stop |66 for a considerable period of time. during thelatter part of which time the cam elevation |84 in the |86 position isbrought into pressure relation with the cam end |88 of a resilientspring conductor |99, see Figs. 1 and 7.

Spring contact |99 is anchored to an insulated support |92, and thecontact is aligned with the ange 58. A conducting wire |94 is attachedto a screw |96 having conducting relation with the contact |99 andanchored in the block |92. The latter is fixedly connected with thefloor |2. Contact |99 carries a point |98 arranged to be moved intoconducting relation with a contact 299 carried by a screw 292 to which Iattach a conductor 294. The switch structure of Fig. 'l operates theelectric motor |29.

Fig. 8 illustrates the motor and selector circuit. Line wires 298 and 29 lead to a source of current, withfthe wire 2|9 electrically connectedwith the clock 44 and the wire 298 connected with the clock through themedium of a wire 2|2. vWire 298 is connected with the terminal 2 |4 of adouble pole switch 2|6. Terminal 2|8 of the switch 2|6 is connected withthe wire 229 through the medium of a wire 224. Wire 229 leads to thereceiving set not illustrated. The second wire to the receiving set isillustrated at 226 and is connected with the terminal 228 of the switch2|6. A wire 239 connects the terminal 232 of the switch 2|6 with thewire 2|9. Switch element 234 may be moved into conducting relation withthe terminal 232 at which time the switch element 236 will beelectrically connected with the terminal 228 through the medium of theelement 238. Under suc-h conditions. the circuit to the set will beclosed asI follows: from the wire 208 to the terminal 2|4, switchelement 236, element 238 and wire 226; from the wire 2|9 to the wire239, terminal 232, switch element 234. wire 224 and wire 229.

To the wire 2|9, I connect a wire 249 leading to a contact 242 of aselector switch 244. The switch element 246 includes a contact 248arranged to be brought into electrical relation with the contact 242.Switch element 246 is electrically connected with a wire 259 connectedwith the wire 229. The primary coil 252 of a transformer 254 isconnected with a wire 256 leading to a contact or terminal 258 arrangedto be electrically connected with the terminal 228 through the medium ofthe element 238 when the switch 2|6 is positioned according to Fig. 8.Coil 252 is connected with the wire 259 through the medium of a wire269. Switch 2|6, of Fig. 8, is in the selector position.

The secondary coil 262 is connected with a wire 264 leading to a contact266. Coil 262 is also connected with a wire 268 which leads to the motor|29. The wire 219 connects the motor |29 with a contact 212 carried by arelay switch `arm 214, which is pivotally mounted on a suitable supportfor movement about the airis `216. Wire 294 is connected with an onrelay 218, while a wire 289 connects the on relay 218 with the off relay292. Wire 289 is connected with the Off relay 282 is connected with awire 284' which is switch 2|6 is positioned according to Fie connectedwith the bracket 34. Shaft |56 is of conducting material, which is alsotrue of the bracket 34 so that the wire 284 will be electrically relatedto the shaft |56. Companion stops |59 to |64 are also of conductingmaterial and are electrically related to the shaft |56.

Wire |94 connected with the spring contact |99 is connected with thewire 264 at one end and at its other end with the bracket ||9. Bracket||9 is of conductive material so as to 'ce electrically related to theshaft ||4. Stops |46 to |52 are of conducting material and are arrangedin electrical relation with the shaft ||4. Motor |29 is of sufficientcapacity to handle the shaft ||4 as well as the receiver condenserthrough the medium of the shaft |28 and the drive between the latter andthe condens-er. The motor operates with a low voltage which low voltagecurrent is supplied because of the transformer 254,

Motor |29 can be energized only when the contact 248 is moved intoelectrical relation with the contact 242. Switch element 246 ispivotally connected at 299 with a bracket 292 secured to the blocks |92by `a screw 294. Wire 259 is anchored to the screw 294, and the bracket292 is of conductive material. A tension spring 296 has one end anchoredat 298 to the bracket 292 and its opposite end anchored to a pin 399.xedly connected with the upper end of the switch element 246. Referringto Fig. 8, the pivotal connection 299 is so located as to be positionedto one side of the tension spring 296 when the switch element 246 ispivoted in either direction. Switch element 246 carries cam surfaces 392and 394 so arranged as to be engaged by certain of the pins 96 whenproperly located on the selector drum |4. Cam surface 392 is alignedwith the zone 12, while cam surface 394 aligns with the zone 14. A pin96 when shifted to align centrally with the zone 12 will be brought intocamming relation with the off cam surface 392 for pivoting the switchelement 245 to the position. of Figs. 3 and 6. Similarly, when one ofthe pins 96 is shifted on the selector drum i4 to align centrally withthe zone 14, that pin will be brought into engagement with. the camsurface 394 for pivoting the switch element 246 to the on position. Inthe on position. the contact 24B on the switch element 246 will contactthe contact 242 for electrically connecting the wire 249 with the wire259.

With the switch 244 closed, assuming that the 8. the circuit to theradio receiving set will be closed as follows: from wire 2|9 throughwires 249 and 259, to wire 220. Wire 2.98 will` then be electricallyconnected with the wire 226 through the medium In operation, switch 2|6is positioned accordf ing to Fig, 8 for selector tuning purposes. Thecircuit to the receiver will then. be closed whew ever the switch 244 isclosed. Closing and opening of the switch 244 is consummated through themedium of two pins 96. One pin is aligned with the on zone 14. while thesecond nin is aligned with the off zone 12. Fig. 2 illustrates suchalignment. Pin 96 in the 399 position in advance of the pin 96 in the3|9 position. The two pins are fifteen minutes apart in that they areassociated with adjacent slots 54. With the t on and. off pins operatingin adjacent slots. the

switch 244 will be closed at the preselected time. which time isdetermined by proper selection of the pin 96 to be aligned with the onzone 14. Indicia |16 correspond to the time reading on the face of theclock 447 so that the switch 244 will be closed at the proper time.

A number of stations may be pretuned to operate the receiver insuccessive fifteen minute periods, or the fifteen minute periods may bespaced at selected intervals. Similarly, one station may be pretuned andthe receiver operated continuously for thirty minutes, forty-fiveminutes, an hour or longer. The length of time is determined by thelocation of the on and off pins 96 associated with the on and off zones14 and 12. The off pin breaks the circuit to the receiver at the end ofthe pretuned period so that the set will require no attention other thanproper setting of the selector mechanism.

Selector drum I4 is rotatable manually to facilitate selection of thepins 96. Opening 64 lends access to the selector drum. After the pinshave been selected, drum I4 is manually rotated for setting the clock atthe proper time after which the clock vn'll rotate the selector drum atthe speed of the hour hand of the clock. Rotation of the selector drumwill bring the pin 95 in the |18 position, for example, into cammingrelation with the companion stop |64. At the same time, spring contact|98 is depressed for closing the circuit through the motor |20. Motor|28 rotates the shaft H4 for bringing the stop |52, for example, intoabutting relation with the companion stop |64 in its horizontal positionto restrain further rotary movement of the shaft. Stop |52 is flxedlyrelated to the shaft and is adjusted so as to stop further rotation ofthe shaft at the moment that the variable condenser of the set has beenprecisely tuned.

Referring to Fig. 8, when the spring contact |90 is depressed forbringing the contacts |98 and 280 into conducting relation, the circuitwill be closed through the on relay 218, at which time the arm 214 willbe pulled in the direction of the relay for establishing conductingrelation be tween the contacts 266 and 212, Thus current will besupplied to the motor |26. Arm 214 is connected with one end of a spring3|2, the other end of which is flxedly anchored to a suitable support.AXis 216 is located to one side of the spring 3|2 when the arm 214 is ineither of its two positions so as to be yieldingly supported in suchpositions. Companion stop |84 does not engage the stop |52 until themoment that the cam elevation |84 in the |86 position passes over thecam end |88 of the conductor |88. As the conductor |98 is freed itseparates the contacts |88 and 288, at which time the stop |52 lies incontacting relation with the companion stop |64 which immediately closesthe circuit through the off relay 282. Relay 282 will then attract thearm 214 to the position of Fig. 8, at which time the spring 3|2 isrendered effective for yieldingly holding the arm in the positionillustrated until such time as the on relay 218 may again be energized.

In Figs. 1, 2 and 4, I illustrate my automatic volume control 3|4. Thevolume control includes a bracket 3|8 having a threaded shank 3| 8extending through the opening 328 in the wall 46. A nut 322 clamps thebracket to the wall. Bracket 356 carries a bar 324, an upright post 326formed integrally with the bar and a second bar 328 paralleling the bar324. Post 326 interconnects the bar 324 and 328 at one end, while across piece or post 330 interconnects the opposite ends through themedium of screws 332. Bars 324 and 328 are grooved at 334 for slidablyreceiving a rack 336 arranged in mesh with a pinion 338 fixed to a shaft340. Bars 324 and 328 are provided with openings 342 for rotatablysupporting the shaft 348, while the shank 3|8 is provided with anopening 344 loosely receiving the shaft. A knob 346 is fixed to theshaft 340 to permit manual rotation thereof.

Upon the rack 336, I mount a resistor 348, which resistor is insulatedfrom the rack through the medium of a suitable strip 353 anchored to theelevations 352 on the rack 336 through the medlum of screws 352.

Post 338 is provided with an opening 354 for slidably receiving a shaft356 having a square reach 358 slidable in the square opening 38|) in thepost 326. A collar 362 is adjustably connected with the shaft 356through the medium of a screw 364. Between the post 338 and the collar362 and upon the shaft 356, I interpose a cornpression spring 366. Thewire 368 of the volume control of the receiver is electrically connectedwith the post 330. Post 330 is in conducting relation with the shaft356, while the collar 362 is also in conducting relation with the shaft.A feeler wire 318 is connected with the collar 362 at one end and hasits other end contacting the resistor 348 and arranged to slidetherealong. The other wire of the volume control circuit of the set isillustrated at 312 and is connected with the resistor at one end. Theother end of the resistor is dead.

The outer end of the squared reach 358 is slotted at 314 to receive aWheel 316 rotatably mounted on a pin 318. Wheel 316 has pressurerelation with the periphery of a volume cam 380 Xedly connected with theshaft |28. Spring 366 urges the shaft 356 in the direction of the volumecam 380. Volume cam 38D is provided with peripheral recesses 382, 384,386 and 388. Recess 382 receives the wheel 316 when the stop |52 ispositioned according to Fig. 1. Movement of the feeler wire 310 alongthe resistor 348 in the direction of the wire 312 thus giving more poweroutput. Recesses 382 to 388 are of different depths so as to vary thepower output. One recess is provided for each of the stops |46' to |52.Recess 382 is operatively related to the stop |52, which stop is alignedwith the zone 82 so that the power output value of the recess .Y

382 will be in accordance with the demands of the broadcasting stationrepresented by that Zone. Recess 388 is associated with the stop |48,while the recess 386 is associated with the stop |46. Recess 384 isassociated with the stop |58. It will thus be seen that the volume cam380 functions as a volume control for each of the broadcasting stationsrepresented by the zones 16, 18, 80 and 94. The number of recesses inthe periphery of the volume cam will depend upon the number of thebroadcasting station zones incorporated in the station selector.

Frequently atmospheric conditions, distance and the like may weaken orstrengthen signals. I provide means whereby the automatic volume controlmay be precisely adjusted. Rack 336 may be shifted longitudinallythrough the medium of the gear 338 manually actuated through the mediumof the' knob 346. Such adjustment of the rack 336 moves the resistor 348relatively to the feeler wire 310. Adjustment of the resistor throughthe manual control increases or decreases the ratios of the recesses 382to 388 in corresponding amounts. It will thus be seen that the manualcontrol incorporated in the automatic volume control permits refinementto be made in the power output of the automatic control.

I claim: 1. An automatic tuning mechanism for radio receivers includinga rotatable condenser shaft adapted to be turned to predetermined radiostation tuning positions, a rotary station selector drum, a time devicefor rotating the selector drum, a motor including a circuit for turningthe condenser shaft, a motor switch in said circuit including momentaryswitch closing means carried by the selector drum, an on, and` o switchincluding a circuit for connection with the receiver circuit, selectorpins shiftable on said drum for actuating the on and ofi` switch atpredetermined times, stops corresponding to different broadcastingstations fixed to the condenser shaft, shiftable companion stops,selector pins shiftable on the selector drum for moving the companionstops into abutting relation with said stops, to stop further rotationof the condenser shaft when rotated to respective tuning positions, saidstops and said companion stops being electrically related and comprisinga part of the circuit associated with the motor, and electrical meansenergized through contact of said stops with their respective companionstops, to maintain a broken circuit through the motor only.

2. An automatic tuning mechanism for radio receivers including arotatable condenser shaft adapted to be turned to predetermined radiostation tuning positions, a rotary station selector drum, a time devicefor rotating theselector drum, a motor including a circuit for turningthe condenser shaft, a motor switch in said circuit including momentaryswitch closing means carried by the selector drum, an on and off switchincluding a circuit for connection with the receiver circuit, selectorpins shiftable on said drum for actuating the on and off switch atpredetermined times, stops corresponding to different broadcastingstations fixed to the' `condenser shaft, shiftable companion stops,selector pins shiftable on the selector drum for moving the companionstops into abutting relation with said stops, to stop further rotationof the condenser shaft whenrotated to respective tuning posil tions,said stops and said companion stops being electrically related and,comprising a part of the circuit associated with the motor, andelectrical means energized through contaotkof one of said stops with itsrespective companion stop, to maintain a broken circuit through themotor only, all of said selector pins being shiftable to neutralpositions on the selector drum.

3. The invention defined in claim one wherein the selector drum isprovided with bar-like members p-aralleling the axis of rotation of thedrum, with the bar-like members spaced to provide slots lfor theselector pinssaid bar-like members having flanges and each selector pinhaving a flange slidably engaging one flange of two bar-like members,and a spring connected with each pin and frictionally engaging theopposite sides of the two fianges engaged by the flange of that pin tofrictionally secure the pin in its different positions.

4. The invention defined in claim one wherein the stops fixed to thecondenser shaft are in the nature of arms projecting radially from thecondenser shaft, said companion stops being in the nature of barspivotally connected to a fixed support intermediate their ends andarranged to be pivoted by their respective 'selector pins to positionthe bars in the path of their respective stops fixed to the condensershaft.

` CURTIS 0. NELSON.

